Moon link tenuous: scientist
The Moon, the Sun and atmospheric pressure are highly unlikely to be causing aftershocks or influencing them, a study shows.
Auckland Predict Weather director Ken Ring says that since the September 4 earthquake he has been able to accurately predict clusters of aftershocks based on the increased gravitation pull from the Moon and the Sun at certain times of the month.
But Canterbury University physics postgraduate student John Holdaway, in his latest force and energy analysis of the aftershocks, says he can find no evidence of a link.
Ring has built a business on his assertions that he can predict the weather based on the Moon's cycles.
Holdaway said: "There's no obvious or significant correlation between the force of gravity by the Sun and the Moon, and the atmospheric pressure, and the number of quakes we are getting or the size of them."
The time of the month should not influence when large aftershocks occur.
"I'm aware that there has been at least one person in the news claiming that the position of the Moon may have affected the quakes in Canterbury, but that seems to be a fairly tenuous assumption, unsupported by much of the scientific evidence at present," Holdaway said. "While it's true that the Moon and Sun exert small forces on the surface of the Earth depending on their relative orientation, these forces do not seem to be strong enough to significantly influence the exact hour or day that any particular quake will occur on."
Some scientific papers suggested there might be about a 0.5 per cent increase in quake numbers because of tidal forces, but not for shakes of magnitude 4.0 or above.
Ring said most of the aftershocks had "occurred on the new or the full Moon".
"I feel that I have been spot-on with predicting them in terms of saying when the clusters will happen around the Moon times. They are getting less because the Moon is moving further away."